The need for improving and evaluating students' cognitive skills, including problem-solving, has been highlighted in both the mathematics education literature and the curricula worldwide. The objective of this study was to assess the problem-solving skills of lower secondary school students using a teacher-based evaluation method, taking into account their grade level, gender, grade-point averages, and mathematics grades. To that end, the Problem-solving Skill Scale was administered to 39 mathematics teachers from 21 schools, for a total of 1010 sixth, seventh, and eighth grade students. Based on the findings, it can be inferred that the students possess an adequate level of problem-solving skills; however, their level of proficiency differed significantly according to their grade levels, gender, grade-point averages, and mathematics grades. This identification of the students' problem-solving skills is expected to guide them towards activities and resources that align with their individual abilities.